Dear Anthony,
Thank you very much for your response. Is it a general case and we can do the 
same for all the other theorems like the n2w_DIV or no? 
Regards,
--- On Mon, 3/4/13, Anthony Fox <[email protected]> wrote:
Hi Hamed,

Yes, the side-condition

n < dimindex (:α)

is redundant. I’ve updated this theorem accordingly.

To get a theorem with no side-conditions we can introduce a MOD:

 wordsTheory.n2w_DIV
 |> Q.SPEC `a MOD dimword(:'a)`
 |> SIMP_RULE (srw_ss()) [wordsTheory.n2w_mod]
 |> GEN_ALL

val it =
   |- ∀a n. n2w (a MOD dimword (:α) DIV 2 ** n) = n2w a ⋙ n:
   thm

It would also have been possible to get to this theorem using word_lsr_n2w as 
the starting point.

Regards,
Anthony

On 4 Mar 2013, at 19:48, hamed nemati <[email protected]> wrote:

> Hello all,
> For Theorems like the following one what is the corresponding theorem if 
> the guard conditions do not hold,  I mean what the n2w_DIV theorem would like 
> if a or n or
>  both of them are greater that dimword (:α).
>    [n2w_DIV
> ]  Theorem
> 
>       |- ∀a n.
>            n < dimindex (:α) ∧ a < dimword (:α) ⇒
> 
>            (n2w (a DIV 2 ** n) = n2w a ⋙ n) 
> 
> do we have module to dimword(:'a) of these two numbers? if no what we can
> do in such a case? Thanks in advance.
> 
> Regards,
> Hamed Nemati
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